Thermal runaway detection system for batteries within enclosures

ABSTRACT

A battery thermal runaway detection sensor system for use within a battery enclosure housing one or more batteries. The system has at least one gas sensor for detecting a venting condition of a battery cell of hydrogen, carbon monoxide or carbon dioxide, and providing a sensed output in real time. A microcontroller determines power management and signal conditioned output on the concentration of specific battery venting gases based on the sensed output from said at least one gas sensor.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application is a divisional of U.S. Pat. Application Serial No.17/021,711, filed on Sep. 15, 2020, and all the benefits accruingtherefrom under 35 U.S.C. 119, the contents of which are hereinincorporated by reference in their entirety.

BACKGROUND

The disclosure relates generally to a detection system for detectingbattery failure and more particularly to a detection system fordetecting thermal runaway of batteries within enclosures, for example,batteries used with electric vehicles, FIG. 2(a), or stationary batteryenergy storage systems, FIG. 2(b).

Referring to FIGS. 1(a), 1(b), thermal runaway in lithium basedbatteries is a process under which an exothermic reaction occurs withina failed cell that increases the internal temperature, which in turnreleases energy that sustains the internal degradation reactions andincreases the temperature until ultimate failure of the cell, oftenaccompanied by explosive release of the electrolyte, and often resultingin fire. In modern lithium batteries, the risk of explosion can bereduced by design to incorporate a controlled venting location in thecell (see FIG. 4 ), but risk of fire and explosion due to thermalrunaway has not been eliminated in most liquid electrolyte lithium-basedbatteries.

Turning back to FIGS. 1(a), 1(b), certain triggers and abuse conditionscan lead batteries, e.g., lithium-ion cells, to breakdown or failure,which in turn can result in a thermal runaway. Thermal runaway can becaused, for example, by external short circuit, internal short circuit(particle, dendrites, separate failure, impact/puncture), overcharge,over-discharge, external heating, or over-heating (self-heating). Withelevated temperatures is the generation of gas. If heat dissipationoccurs faster than heat generation, there can be a safe outcome.

If left unhindered, or but if the heat cannot be dissipated faster thanit is being generated, this can result in a rapid increase intemperature, release of flammable and hazardous gases during venting,flames, and explosion. This can especially be problematic for vehicleshaving large format battery systems, as shown in FIG. 3 , and inparticular battery electric vehicles and stationary storage, where thethermal runaway of a single cell (FIG. 4 ) can lead to a cascade ofthermal runaway events that can engulf the entire pack, resulting incatastrophic fire and release of hazardous gases.

Sensors have been developed to detect thermal runaway. However, simplegas sensors, such as a hydrocarbon sensor, can only detect electrolytegas concentration, but suffer from cross sensitivity to other gases aswell as substantial drift and so make poor long-life thermal runawaydetection sensors.

No admission is made that any reference cited herein constitutes priorart. Applicant expressly reserves the right to challenge the accuracyand pertinence of any cited documents and information.

SUMMARY

A detection system is disclosed that addresses the challenges of fast,robust thermal runaway detection within a battery enclosure that isgenerally agnostic to electrochemistry, cell packaging (cylindrical,prismatic, or pouch), as well as battery configuration (series/parallel)by identifying attributes of initial cell venting that are sharedbetween numerous design types and responding to venting gases of afailing cell.

During thermal runaway, the cell converts substantial cathode andelectrolyte material into gas and vents the pressurized gas mixture intime spans of seconds when the faulted cell is at a high State ofCharge, FIG. 1(b). Of the typical cell chemistries such aslithium-manganese-cobalt-oxide (NMC) batteries, Lithium Cobalt Oxide(LCO), and Lithium Iron Phosphate (LFP) batteries, thermal runawaytesting has shown the release of several gases, including largequantities of carbon dioxide and hydrogen, see FIG. 5 . Carbon dioxideis generally evolved during the oxidation reaction of carbonate solventsand hydrogen is generally released as a product of the reduction ofwater deriving from combustion reactions by carbon monoxide and/or freelithium, with methane and ethane compounds also present from reductionreactions of the electrolyte and ethylene carbonate at the lithiatedanode.

This summary is not intended to identify essential features of theclaimed subject matter, nor is it intended for use in determining thescope of the claimed subject matter. It is to be understood that boththe foregoing general description and the following detailed descriptionare exemplary and are intended to provide an overview or framework tounderstand the nature and character of the disclosure.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying drawings are incorporated in and constitute a part ofthis specification. It is to be understood that the drawings illustrateonly some examples of the disclosure and other examples or combinationsof various examples that are not specifically illustrated in the figuresmay still fall within the scope of this disclosure. Examples will now bedescribed with additional detail through the use of the drawings, inwhich:

FIG. 1(a) is a flow diagram showing the progression of thermal runaway;

FIG. 1(b) is a chart of thermal runaway and temperature;

FIG. 2(a) is a typical battery pack in an electric vehicle;

FIG. 2(b) is a drawing of a typical battery pack in an energy stationarystorage enclosure;

FIG. 3 shows a battery thermal runaway detector;

FIG. 4 shows a typical battery cell before and after thermal runaway;

FIG. 5 is a diagram of gas released from thermal runaway events in cellswith different electro-chemistries: LCO/NMC, NMC, and LFP;

FIG. 6 is a plot of cascading thermal runaway propagating through packenclosure wherein initial cell triggered thermal runaway in severaladjacent cells;

FIG. 7 is a plot of hydrogen concentration rise immediately afterinitial vent followed by slight pressure rise within the enclosure overone minute later as gas expansion exceeds pack level venting capability;

FIG. 8 is a plot of thermal runaway initiation showing rapid carbondioxide concentration rise within the enclosure; and

FIG. 9 is a schematic of thermal runaway management system.

DETAILED DESCRIPTION

In describing the illustrative, non-limiting embodiments illustrated inthe drawings, specific terminology will be resorted to for the sake ofclarity. However, the disclosure is not intended to be limited to thespecific terms so selected, and it is to be understood that eachspecific term includes all technical equivalents that operate in similarmanner to accomplish a similar purpose. Several embodiments aredescribed for illustrative purposes, it being understood that thedescription and claims are not limited to the illustrated embodimentsand other embodiments not specifically shown in the drawings may also bewithin the scope of this disclosure.

The Battery Thermal Runaway Detector is predisposed within the voidairspace of a typical battery enclosure, for example as shown in FIG. 3. The enclosure completely surrounds one or more battery modules, eachbattery module having one or more battery cells aligned in parallel orseries with one another. The battery cells of each module are inelectrical communication with the adjacent cells, and the batterymodules are in electrical communication with each adjacent module. Abattery controller is in communication with each battery module and/orbattery cell. The battery controller can operate each battery celleither directly or via the module, such as to turn the cell on/off orcontrol the voltage output of each cell.

The enclosure protects the battery cells and modules from water, debris,and to protect users and occupants from the electrical hazards withinthe enclosure. Enclosure void space volumes (the volume of air spacewithin the enclosure) can vary from as little as a few liters to as muchas 200 or more liters, typically containing air. The battery enclosureis generally provided with air venting features inclusive of a single ormultiple small openings that allow for pressure equilibrium inside andoutside the enclosure to prevent strain and damage to the pack. Theseopenings are generally protected with hydrophobic membranes that allowfor air exchange but prevent the direct flow of liquid water into theenclosure. The enclosure may also include valves or similar devices toallow over pressure from a thermal runaway to safely vent from theenclosure, reducing risk of explosion and harmful shrapnel.

Turning to FIG. 9 , a thermal runaway detector or detection system 100is shown in accordance with one non-limiting example embodiment of thepresent disclosure. The detection system 100 resides within the batteryenclosure void space as in FIG. 3 and includes a primary detector, herea gas detector 110. The detection system 100 also includes a pressuresensor 112, relative humidity (RH) sensor 114, and/or temperature sensor116. The gas detector 110 has one or more sensors, and in one embodimenthas a CO₂ gas sensor, carbon monoxide sensor, and/or a H₂ gas sensor.The detectors/sensors 110-116 are positioned about the enclosure, andany suitable combination of detectors and/or sensors 110-116 can beutilized.

The thermal runaway detection system 100 also contains a voltageregulator 120 that provides and regulates sufficient power to operatethe sensors 110-116, microcontroller or microprocessor 118, andcommunications transceiver 122. The sensor elements 110-116 areelectrically connected to the microcontroller 118 within the detectionsystem 100. The microcontroller 118 interprets the sensor output fromeach of the sensors 110-116, and provides necessary signal conditioningto convert the raw sensor signals to engineering values for eachcomponent. The values are then transmitted to the communicationstransceiver 122, which provides a data stream of sensor information tothe battery management system master controller or other electronicmonitoring system.

When a CO₂ gas sensor 110 is used as one of the primary gas sensors 110,it detects carbon dioxide levels in the enclosure (FIG. 3 ) and has longterm reliability and a fast response time (under 6 seconds to record anevent). Carbon dioxide background concentration levels are generallyless than 1,000 ppm, during a battery cell venting conditions, theseconcentrations can easily exceed 60,000 ppm within the enclosure,providing very robust gas signal for detection, as shown in FIG. 8 .With ejecta speeds during venting often exceeding 200 m/s, diffusion ofcarbon dioxide within the enclosure void space happens very rapidly,reaching the gas sensor 110 within 2 seconds or less regardless of thesensor proximity to the venting cell.

In a similar fashion, background concentrations of hydrogen inatmospheric air are generally around 200 to 300 ppb. Under battery cellventing conditions, hydrogen concentrations inside the battery enclosurecan easily exceed 140,000 ppm, also providing a robust signal to noiseratio for gas detection, as shown in FIG. 7 .

The pressure sensor 112 detects the gas pressure levels in the voidspace of the battery enclosure. Nominal air pressure within theenclosure approximates atmospheric pressure. During thermal runawayventing, the pressure may rise abruptly if the venting phase is highlyenergetic, as in the case of a cell that is at 100 percent state ofcharge as shown in FIG. 6 . But the initial accompanying pressure risemay also be very low, especially in the case of smaller cells or cellswhose state of charge is much lower, as shown in FIG. 8 . While there isdependence on the enclosure venting system, an increase in gas pressureor temperature can provide information on the rate of thermal runaway.The pressure sensor 112 is small and low cost, has a fast time responsewith low power consumption, but has been shown to provide poor dataduring slow venting phenomenon where the battery enclosure ventingsystem allows release of the trapped gas at a rate that offsets gasgeneration. When used to supplement the gas sensor 110, however, thepressure sensor 112 can provide valuable insight as to the progressionof the thermal runaway as it cascades from the initiation cell toadjacent cells within the enclosure, as shown in FIG. 6 , where theconsecutive increases in hydrogen gas concentration and accompanyingpressure spikes indicate that the thermal runaway has progressed toadditional cells.

The temperature sensor 116 detects the temperature within the enclosurevoid space, and like the pressure sensor 112, can be used in conjunctionwith the gas sensor 110 to estimate the rate of progression of thethermal runaway (FIG. 6 ). Progressive increases in temperature thataccompany each successive cell thermal runaway provide critical data indetermine if the reaction has stopped or is progressing at such a rateas to require immediate safety measures, such as disabling the systemproviding protective countermeasures.

The relative humidity sensor 114 monitors the humidity within the voidspace of the enclosure and can also be used in conjunction with the gassensor 110 to observe substantial changes in water vapor within theenclosure indicative of the formation of water vapor due to thedecomposition reaction.

The detection system 100 can be utilized for a variety of suitableapplications. In the embodiment shown in FIGS. 2(a), 3 , the detectionsystem 100 is implemented in a vehicle having a battery enclosure, apower distribution unit, and a battery controller and/or Motor ControlUnit (MCU). The battery enclosure can be made up of a plurality ofbattery cells and housed inside a battery enclosure.

The sensors 110-116 each output a sensed signal to a processing device,such as the microcontroller 118. The microcontroller 118 converts theanalog sensor signal to engineering values and transmits that data, suchas in the form of an alarm signal or output signal, to the BatteryManagement System via a wired or wireless transceiver 122. Themicrocontroller 118 can also determine if the values from the sensors110-116 exceed a critical threshold value for that sensor to indicatecell venting as well as provide algorithms to determine if the sensors110-116 are operating normally and within specifications. The detectionsystem 100 may utilize redundant sensors 110-116 to meet Safety IndexLevels.

One or more of the sensors 110-116 are located in a free space withinthe battery enclosure (FIG. 3 ) of the vehicle, so that the sensors110-116 are in communication (e.g., gas or pressure communication) withthe air space proximate to the batteries and/or battery compartment andreceive and detect the conditions resulting from a battery cell venting.The sensors 110-116 provide the output to the processing device 118,which can determine if the sensed condition exceeds a predeterminedthreshold or if there is a rapid change in the sensed condition. Theentire system 100, including the sensors 110-116, microcontroller 118,regulator 120, and transceiver 122, can all be housed in a single sensorhousing and positioned at one location in the battery compartment. Inanother embodiment, the system 100 can be separate devices each withtheir own housing and each housing positioned at separate locations inthe battery compartment, including surface mounted on the batterymanagement system electronics.

As shown and described, the detection system addresses the problem ofrobust detection of thermal runaway in lithium ion batteries, where theoutgassing precursor to thermal runaway can occur in timespans ofseconds or hours. The detection system measures multiple physicalparameters of the outgassing event that can allow detection of rapidthermal runaway as well as slower events. The multiple detectiontechnology reduces the risk of alpha/beta errors and provides sufficientredundancy to meet market safety requirements. The system measures, at aminimum, hydrogen and/or carbon dioxide concentration, and may besupplemented with air pressure and or temperature and humidity in theenclosure.

In other variants, the detection system could also include hydrocarbondetection of the electrolyte, including methane, esters, and ethanegases. During the initial cell venting that precedes thermal runaway,vented gases include H2, CO, CO₂, and hydrocarbons in sufficientconcentration to be detected by the individual sensors. By combiningthem into a single sensor platform with signal conditioning andanalysis, it is possible to determine with relative certainty that theevent is a single cell undergoing thermal runaway, and by monitoring thegases simultaneously, determine the difference between less urgentelectrolyte leakage and more urgent thermal runaway condition. The useof the principle of thermal conductivity for hydrogen and non-dispersiveInfrared measurement of CO₂ sensor are robust, absolute measurementdevices that have limited cross sensitivity to other gases, making themideal for this application where there is little or no opportunity torecalibrate or service the devices in the field.

Referring more specifically to FIG. 6 , an example runaway is shown. Inthis illustrative example, the thermal runaway cascades from one cell toadjacent cells. Starting at T=0, the battery system is operating undernormal conditions, and the hydrogen level 150, temperature 160, andpressure 170 are all normal. At a first time period, T=1, a first singlebattery cell of a first battery module experiences thermal runaway. As aresult, it releases a gas, here Hydrogen. The hydrogen sensor of the gasdetector 110 measures the hydrogen level, and has a sensed gas leveloutput. It transmits the sensed gas level output to the microcontroller118. In addition, the pressure sensor 112, detects the pressure, and hasa sensed pressure output. It then transmits the sensed pressure outputto the microcontroller 118. Further, the temperature sensor 116 measuresthe temperature in the enclosure, and provides a sensed temperatureoutput. It transmits the sensed temperature output to themicrocontroller 118.

The sensors 110-116 immediately send the sensed outputs to themicrocontroller 118 in real time without delay or manual intervention.The sensors 110-116 can send sensed outputs to the microcontroller 118continuously or at intermittent random or predetermined periods (such asseveral times a second).

In the example embodiment of FIG. 6 , a cascading thermal runaway eventis shown propagating through pack enclosures where initial cell triggersthermal runaway in adjacent cells. The microcontroller 118 receives asensed gas, pressure and temperature outputs from the gas, pressure andtemperature sensors 110, 112, 116, respectively. At T=1, the hydrogengas level 150 and pressure 170 both exhibit a spike. However, thetemperature 160 only increases slightly. The venting in the batteryenclosure enables the pressure 170 to quickly dissipate back to normallevels, though the Hydrogen vents more slowly and stays at an elevatedlevel. Based on these conditions and receipt of the sensed outputs, themicrocontroller 118 determines that at least a first battery cell hasexperienced a thermal runaway event, and generates an alarm signal thatit sends to the battery controller. The battery controller, in response,might for example take a first response, such as to indicate to theoperator that service is needed, to reduce the voltage requirements forthe battery module, or to control the battery so that it does not get ashot.

At T=2 in the example embodiment of FIG. 6 , another cell experiences athermal runaway. Here, the microprocessor 118 determines, based onsensed outputs from the gas sensor 150 and pressure sensor 160, thatthere is another spike in gas and pressure, respectively, and that thetemperature has again increased slightly. The pressure again returns tonormal rather quickly due to venting conditions, but the temperature andhydrogen level continue a rising pattern. Accordingly, themicroprocessor 118 determines that another thermal runaway event hasoccurred, and sends another alarm signal to the battery controller. Thebattery controller can continue to take the same response, or canescalate the response such as by shortening the alert response time, forexample by indicating that immediate service is needed, or by turningoff one or more of the battery modules. The microcontroller 118determines that there are further spikes at T=3, 4. The various levelsof gas, temperature and pressure may vary based on venting conditionsand the specific thermal runaway event. For example, following T=4, thepressure may decrease as the enclosure hydrophobic vents fail, thoughspikes occur with each successive cell thermal runaway event asadditional cells fail within the enclosure. The microcontroller 118 orbattery controller can further determine that there is a cascadingpattern to the event and take additional responsive actions. Theresponsive actions can be sent from the battery controller to themicrocontroller 118 via the transceiver 122, which then controlsoperation of the cells and modules.

Turning to FIG. 7 , another example thermal runaway event is shown.Here, the system 100 has a gas sensor 110, here a Hydrogen sensor, and apressure sensor 112. At T=1, the hydrogen concentration 150 risesimmediately after initial vent, followed by a slight pressure 170increase at T=2 (one minute after T=1) within the enclosure as gasexpansion exceeds pack level venting capability. Thus, at T=1, themicroprocessor 118 generates an alert that thermal runaway hasinitiated. The pressure rise at T2 in FIG. 7 demonstrates the delayedresponse of pressure signal in this instance, wherein there existshydrogen gas above the Lower Exposure Limit at T1, yet the pressure doesnot substantially increase for over one minute.

Turning to FIG. 8 , yet another example embodiment is shown. Here, thegas detector 110 is a carbon dioxide sensor. The plot shows rapid carbondioxide concentration 150 rise within the enclosure, while pressure 170remains the same and the temperature 160 exhibits a slight increase. AtT=2, the microcontroller 118 determines that a thermal runaway hasoccurred, and generates an alarm that it sends to the batterycontroller.

Thus, the microcontroller 118 uses the sensed outputs from the gas,pressure, RH, and/or temperature sensors 110, 112, 114, 116,respectively, to determine if there is a thermal runaway event or othercondition within the battery enclosure. The microcontroller 118 can basethat determination on a single sensed output, or on a combination ofsensed outputs. For example, the microcontroller 118 can determine basedon the presence of a gas spike alone, that a thermal runaway might beoccurring and then refer to the sensed pressure output and/or the sensedtemperature output to determine if the thermal runaway event iscascading to additional cells throughout the pack by utilizing acombination of gas measurement to determine initial thermal runawayevent and monitoring for increases in pressure or temperature to assessthe magnitude of the event. Increasing temperature or pressure withinthe pack coincident with high gas concentration levels are indicativethat countermeasures have not isolated the event to a single cell, andgenerate an alert escalating a response. For example, the initial alertcould be to notify the vehicle owner to take the vehicle in for serviceas soon as possible, and the escalating alert could be to notify thevehicle occupants to bring the vehicle to the side of the road, exit thevehicle and the BMS would shut the vehicle down except for the heatexchanger system to try to slow the process down. However, if thetemperature and pressure do not increase, the microcontroller 118 candetermine that the thermal event has ceased and has been isolated to asingle cell or group of cells, and not generate an alert escalating theresponse. Thus, in the example given, the alert would continue to notifythe vehicle owner to have the vehicle serviced.

It is noted that a microcontroller 118 is provided to receive the sensedoutputs, determine spikes and send an alarm to the battery controllervia the transceiver 122. However, the microcontroller operation caninstead be performed by the battery controller itself, and sensedoutputs can be transmitted, via the transceiver, to the batterycontroller. And responsive action signals can be sent directly from thebattery controller to the cells, via the transceiver 122.

Advantages of the detection system 100 include, for example, the use ofknown, validated and field proven sensor technology, leveraging aspecific combination of sensors to allow for layering of the detectionmechanisms related to chemical and thermal physics of phenomenaassociated with the thermal runaway event. The system requires little,if any customization to be suited for various xEV enclosure size/cellconfiguration/electrochemistry. The system also has very fast timeresponse (generally 3 to 5 seconds) in an environment where positivedetection of thermal runaway requires fast response with minimal risk ofmissed/false detection. The system is compact and can be operated inmultiple modes for reduced parasitic power consumption when the batteryenclosure is neither actively charging nor discharging. These modes canbe controlled within the sensor assembly 100 utilizing informationreceived from the battery Management system on active mode (eitherdriving or charging, where fast detection is critical and powerconsumption less important, or in passive mode, where power consumptionis critical and sampling rate can be reduced to reduce device powerconsumption.

The system and method of the present invention include operation by oneor more processing devices, including the microprocessor 118. It isnoted that the processing device can be any suitable device, such as aprocessor, microprocessor, controller, application specific integratedcircuit (ASIC), or the like. The processing devices can be used incombination with other suitable components, such as a display device,memory or storage device, input device (touchscreen), wireless module(for RF, Bluetooth, infrared, WiFi, etc.). The information may be storedon a computer medium such as a computer hard drive, or on any otherappropriate data storage device, which can be located at or incommunication with the processing device. The entire process isconducted automatically by the processing device, and without any manualinteraction. Accordingly, unless indicated otherwise the process canoccur substantially in real-time without any delays or manual action.

It will be apparent to those skilled in the art having the benefit ofthe teachings presented in the foregoing descriptions and the associateddrawings that modifications, combinations, sub-combinations, andvariations can be made without departing from the spirit or scope ofthis disclosure. Likewise, the various examples described may be usedindividually or in combination with other examples. Those skilled in theart will appreciate various combinations of examples not specificallydescribed or illustrated herein that are still within the scope of thisdisclosure. In this respect, it is to be understood that the disclosureis not limited to the specific examples set forth and the examples ofthe disclosure are intended to be illustrative, not limiting.

As used in this specification and the appended claims, the singularforms “a”, “an” and “the” include plural referents, unless the contextclearly dictates otherwise. Similarly, the adjective “another,” whenused to introduce an element, is intended to mean one or more elements.The terms “comprising,” “including,” “having” and similar terms areintended to be inclusive such that there may be additional elementsother than the listed elements.

Additionally, where a method described above or a method claim belowdoes not explicitly require an order to be followed by its steps or anorder is otherwise not required based on the description or claimlanguage, it is not intended that any particular order be inferred.Likewise, where a method claim below does not explicitly recite a stepmentioned in the description above, it should not be assumed that thestep is required by the claim.

What is claimed is:
 1. A battery thermal runaway detection system foruse within a battery enclosure housing one or more batteries, thedetection system comprising: at least one gas sensor comprising ahydrogen sensor configured to detect greater than 300 ppm hydrogen, or acarbon dioxide sensor configured to detect greater than 1,000 ppm carbondioxide, and configured to provide a sensed output in real time; amicrocontroller electrically connected to the at least one gas sensorand configured to determine power management and provide a signalconditioned output of a concentration of the hydrogen or the carbondioxide based on the sensed output from the at least one gas sensor; abattery controller connected to the microcontroller; and at least onesecondary sensor for detecting a secondary condition of the battery andproviding information on a rate of progression of the cell venting andthermal runaway in real time including pressure or temperature, whereinsaid microcontroller provides a rate of progression of the thermalrunaway based on the provided information from said secondary sensor. 2.The detection system of claim 1, wherein said at least one gas sensordetects a level of hydrogen gas or carbon dioxide gas in the batteryenclosure housing.
 3. The detection system of claim 1, wherein said atleast one secondary sensor detects a pressure or temperature in thebattery enclosure housing to determine rate of progression of theventing/thermal runaway.
 4. The detection system of claim 1, furthercomprising a sensor housing enclosing said at least one gas sensor. 5.The detection system of claim 1, further comprising a hydrocarbon sensorconfigured to allow for differentiation between electrolyte leakage andventing/thermal runaway.
 6. The detection system of claim 5, wherein thesystem is configured to send a wake up command to the battery controllerupon detection of venting/thermal runaway.
 7. The detection system ofclaim 1, further comprising software embedded within the microcontrollerconfigured to determine if a threshold for thermal runaway has beenexceeded and to send an alarm to the battery controller or a chargingsystem controller.
 8. The detection system of claim 1, furthercomprising a multichip printed circuit board mounted on a batterycontroller printed circuit board.
 9. The detection system of claim 1,further comprising a power management system configured to allow for afast data acquisition mode during active battery systemcharging/discharging, and a reduced acquisition rate/lower power modewhen the battery system is neither charging nor discharging.
 10. Thedetection system of claim 1, wherein the at least one gas sensorcomprises two hydrogen sensors, two carbon dioxide sensors, or acombination of two hydrogen sensors and two carbon dioxide sensors. 11.The detection system of claim 1, further comprising a humidity sensor.12. The detection system of claim 1, wherein the at least one gas sensorcomprises a hydrogen sensor configured to detect 300 ppb to 140,000 ppmhydrogen and a carbon dioxide sensor configured to detect 1,000 ppm to60,000 ppm carbon dioxide.
 13. The detection system of claim 1, whereinthe hydrogen sensor is configured to detect 300 ppb to 140,000 ppmhydrogen.
 14. The detection system of claim 1, wherein the carbondioxide sensor is configured to detect 1,000 ppm to 60,000 ppm carbondioxide.
 15. The detection system of claim 1, wherein the batterycontroller is connected to the microcontroller by a wired connection.16. The detection system of claim 1, wherein the battery controller isconnected to the microcontroller by a wireless connection.
 17. A systemto detect battery cell venting, utilizing hydrogen gas or carbon dioxidegas sensor elements providing analog output to a battery controller.